swift - 如何在 swift 中为选取框/滚动文本效果创建一个简单的 UILabel 子类？

Question

正如您在上面看到的，我试图编写一个简单的(!)UILabel 子类，以便在标签文本太长时制作选取框或滚动文本效果。我知道那里已经有很好的类(class)(例如 https://cocoapods.org/pods/MarqueeLabel )，但我想自己做 :)

在下方您可以看到我当前的类(class)。我也无法解决新标签向右滚动的问题，但还有第三个标签不应该存在。我认为这是标签本身。但是，当我尝试用该标签替换第一个附加标签时，我将无法工作。我希望它不会太困惑:/

对我来说很重要的是，我只需将 Storyboard 中的类分配给标签。这样就不需要去添加代码，例如在 View Controller 中(在 socket 旁边)。我希望很清楚我想要什么 :D

再说一遍:

• UILabel 的简单子(monad)类
• 滚动标签
• 应该在其他类中没有任何额外代码的情况下工作(除了改变标签文本的导出，例如，......)

(这是我的第一个自己的子类，所以请随时教我如何正确地做它:))

非常感谢!

目前还不完美，但这是我目前的类(class):

import UIKit

class LoopLabel: UILabel {

    var labelText : String?
    var rect0: CGRect!
    var rect1: CGRect!
    var labelArray = [UILabel]()
    var isStop = false
    var timeInterval: TimeInterval!
    let leadingBuffer = CGFloat(25.0)
    let loopStartDelay = 2.0

   required public init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.lineBreakMode = .byClipping
   }

    override var text: String? {
        didSet {
            labelText = text
            setup()
        }
    }

    func setup() {
        let label = UILabel()
        label.frame = CGRect.zero
        label.text = labelText

        timeInterval = TimeInterval((labelText?.characters.count)! / 5)
        let sizeOfText = label.sizeThatFits(CGSize.zero)
        let textIsTooLong = sizeOfText.width > frame.size.width ? true : false

        rect0 = CGRect(x: leadingBuffer, y: 0, width: sizeOfText.width, height: self.bounds.size.height)
        rect1 = CGRect(x: rect0.origin.x + rect0.size.width, y: 0, width: sizeOfText.width, height: self.bounds.size.height)
        label.frame = rect0

        super.clipsToBounds = true
        labelArray.append(label)
        self.addSubview(label)

        self.frame = CGRect(origin: self.frame.origin, size: CGSize(width: 0, height: 0))

        if textIsTooLong {
            let additionalLabel = UILabel(frame: rect1)
            additionalLabel.text = labelText
            self.addSubview(additionalLabel)

            labelArray.append(additionalLabel)

            animateLabelText()
        }
    }

    func animateLabelText() {
        if(!isStop) {
            let labelAtIndex0 = labelArray[0]
            let labelAtIndex1 = labelArray[1]

            UIView.animate(withDuration: timeInterval, delay: loopStartDelay, options: [.curveLinear], animations: {
                labelAtIndex0.frame = CGRect(x: -self.rect0.size.width,y: 0,width: self.rect0.size.width,height: self.rect0.size.height)
                labelAtIndex1.frame = CGRect(x: labelAtIndex0.frame.origin.x + labelAtIndex0.frame.size.width,y: 0,width: labelAtIndex1.frame.size.width,height: labelAtIndex1.frame.size.height)
            }, completion: { finishied in
                labelAtIndex0.frame = self.rect1
                labelAtIndex1.frame = self.rect0

                self.labelArray[0] = labelAtIndex1
                self.labelArray[1] = labelAtIndex0
                self.animateLabelText()
            })
        } else {
            self.layer.removeAllAnimations()
        }
    }
}

Answer 1

首先，如果您不需要从外部访问变量，尤其是 labelText(因为您使用的是要设置的计算属性文本)，我会将变量设为私有(private)。

其次，由于您将标签添加为 subview ，我宁愿使用 UIView 作为容器而不是 UILabel。 Storyboard 中的唯一区别是添加了 View 而不是标签。

第三，如果您使用这种方法，则不应将( View 的)框架设置为零。

类似的东西会做:

import UIKit

class LoopLabelView: UIView {

    private var labelText : String?
    private var rect0: CGRect!
    private var rect1: CGRect!
    private var labelArray = [UILabel]()
    private var isStop = false
    private var timeInterval: TimeInterval!
    private let leadingBuffer = CGFloat(25.0)
    private let loopStartDelay = 2.0

    required public init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

    var text: String? {
        didSet {
            labelText = text
            setup()
        }
    }

    func setup() {
        self.backgroundColor = UIColor.yellow
        let label = UILabel()
        label.text = labelText
        label.frame = CGRect.zero

        timeInterval = TimeInterval((labelText?.characters.count)! / 5)
        let sizeOfText = label.sizeThatFits(CGSize.zero)
        let textIsTooLong = sizeOfText.width > frame.size.width ? true : false

        rect0 = CGRect(x: leadingBuffer, y: 0, width: sizeOfText.width, height: self.bounds.size.height)
        rect1 = CGRect(x: rect0.origin.x + rect0.size.width, y: 0, width: sizeOfText.width, height: self.bounds.size.height)
        label.frame = rect0

        super.clipsToBounds = true
        labelArray.append(label)
        self.addSubview(label)

        //self.frame = CGRect(origin: self.frame.origin, size: CGSize(width: 0, height: 0))

        if textIsTooLong {
            let additionalLabel = UILabel(frame: rect1)
            additionalLabel.text = labelText
            self.addSubview(additionalLabel)

            labelArray.append(additionalLabel)

            animateLabelText()
        }
    }

    func animateLabelText() {
        if(!isStop) {
            let labelAtIndex0 = labelArray[0]
            let labelAtIndex1 = labelArray[1]

            UIView.animate(withDuration: timeInterval, delay: loopStartDelay, options: [.curveLinear], animations: {
                labelAtIndex0.frame = CGRect(x: -self.rect0.size.width,y: 0,width: self.rect0.size.width,height: self.rect0.size.height)
                labelAtIndex1.frame = CGRect(x: labelAtIndex0.frame.origin.x + labelAtIndex0.frame.size.width,y: 0,width: labelAtIndex1.frame.size.width,height: labelAtIndex1.frame.size.height)
            }, completion: { finishied in
                labelAtIndex0.frame = self.rect1
                labelAtIndex1.frame = self.rect0

                self.labelArray[0] = labelAtIndex1
                self.labelArray[1] = labelAtIndex0
                self.animateLabelText()
            })
        } else {
            self.layer.removeAllAnimations()
        }
    }
}